content/child: Remove use of MessageLoopProxy and deprecated MessageLoop APIs

components/printing/test/print_mock_render_thread.cc

Index: components/printing/test/print_mock_render_thread.cc
diff --git a/components/printing/test/print_mock_render_thread.cc b/components/printing/test/print_mock_render_thread.cc
index 4cf3b742c1e0c31cb55182f5bf255ade4bf0e25d..294f9866147f68646b1572078f3e3b6d3e539ed0 100644
--- a/components/printing/test/print_mock_render_thread.cc
+++ b/components/printing/test/print_mock_render_thread.cc
@@ -36,7 +36,7 @@ PrintMockRenderThread::PrintMockRenderThread()
 PrintMockRenderThread::~PrintMockRenderThread() {
 }
 
-scoped_refptr<base::MessageLoopProxy>
+scoped_refptr<base::SingleThreadTaskRunner>
 PrintMockRenderThread::GetIOMessageLoopProxy() {
   return io_message_loop_proxy_;
 }